1.Field of the Invention
2. Prior Art
In signal transmission applications, the choice of coaxial cable for conducting the signal is usually determined by the distance between connection points, the signal frequency, the maximum bend radius required, and the connector space available in a particular transmitting and/or receiving device. The longer the cable and the higher the frequency used, the larger the outside diameter needs to be to prevent excessive signal loss. Traditional coaxial cable applications such as Cable TV, Broadband data, and microwave signal transmission, employ coaxial cables with O.D.""s of 0.25-1 inches for distances of 50-1000 feet. In indoor equipment, the shorter distance requirements (typically 6-24 inches), the limitations of limited space and tighter bend radius requirements are overcome by using smaller coaxial cables with O.D.""s of 0.1-0.14 inches. These small OD cables typically require the use of precision micro-connectors such as SMA, SMB and MCX, which must be connected to the cable in a more or less controlled setting such as a laboratory with precise equipment to both hold and electrically attach the cable to the connectors. The central conductor for such microcoaxial cables is usually attached to the connector by either soldering directly to a fixed center pin in the connector, or soldering or crimping the central conductor to a separate small center pin which is then inserted into the connector. The soldering method requires both electricity, and a clean, well lighed area for assembly. The use of small separate center pins, with a diameter of about 0.040 inch, need careful handing and holding during assembly. The installer needs to hold the pin, place it over the cable center conductor, and then perform the solder or crimp procedure.
With the increased demands on broadband network centers and field located hubs, there exists a need for higher density coaxial cable bundles having as many as 200 coaxial cables connected between equipment locations 100 feet apart. These new high-density cable assemblies now require field-installable connectors that are installed in lab environments. The high-density equipment backplanes also require microcoaxial cable connectors rather than larger connectors used when only a few low density cables are involved. The new cable requirements have been met with the development of lower loss microcoaxial cable bundles containing as many as 12 coaxial cables (each with a 0.1 in. OD) within in a 0.45 inch diameter jacket. There is a need for a reliable method of attaching these microcoaxial cable connectors to the microcoaxial cables in the field without the need for soldering and special handling equipment. A problem encountered during field installation of microcoaxial cable connectors is chemical contamination of conductive parts of the assembly from the installer""s hands. Precision microcoaxial cable connectors are usually plated with gold to limit oxidation and thus require a level of cleanliness to insure proper performance. It is very difficult to insure this level of clean handling when the installer is required to manually grasp the connection center pin in the microcoaxial connector during installation.
Coaxial cables with larger center conductors of over 0.031 in. (0.8 mm) usually use the central conductor as the male center pin within the (assembled) male connector. The central conductor is then inserted directly into the female receptacle that comprises a mating seizing pin. Smaller cables require a male pin to first be attached to the (smaller) central conductor in order to confer the rigidity to the male pin needed to overcome the insertion force required for mating engagement with the female receptacle. Even with additional fixed center pins, the insertion force required for secure engagement can still be limited by the weaker section of the small central conductor not supported by the larger fixed pin.
Coaxial cable connector construction and installation is well known in the established art. The present inventor, in copending U.S. patent application Ser. No. 09/599,059, filed Jun. 21, 2000, U.S. Pat. No. 6,217,383 discloses a compression-type coaxial cable connector. The connector, and each of the components associated therewith, has an axial conduit coextensive with the length thereof. When the prepared end of a coaxial cable is advanced through the conduit into the body portion, a shank separates the outer protective jacket and conductive braid of the cable from the dielectric core and interposes the barbed portion of the tubular shank therebetween. A compression sleeve, with the assistance of a compression tool, compresses the cable jacket and braid providing secure attachment.
Stirling, in U.S. Pat. No. 5,007,861, discloses a crimpless coaxial cable connector which can be secured to a cable simply by pushing the cable into the connector and subsequently pulling it back. The body of the connector has a bushing mounted within it near the cable-receiving end having a conduit dimensioned to receive the cable. The body of the connector also has within it an annular mandrel having a bore to receive the stripped core of the cable, and having a sleeve adapted to engage the cable beneath the jacket by pushing the cable and the mandrel together.
Another radial compression type of coaxial cable connector of the type generally used today for forming an electrical connection between a central conductor within the coaxial cable and a mating fixture is described in detail in U.S. Pat. No. 5,632,651 to Szegda. Various other coaxial cable connectors adapted to from a secure, electrically conductive connection between a coaxial cable and a threaded female port have been developed. Such prior art connectors are discussed, for example, in U.S. Pat. No. 5,024,606 to Ming-Hua, U.S. Pat. No. 4,280,749 to Hemmer, U.S. Pat. No. 4,593,964 to Forney, Jr. et al., U.S. Pat. No. 5,073,129 to Szegda and U.S. Pat. No. 5,651,699 to Holliday. U.S. Pat. No. 5,879,191 to Burris, discusses prior art efforts to provide a coaxial connector which is moisture-proof and minimizes radiative loss of signal from the cable.
All of the above-referenced connectors require that a stripped length of the coaxial cable"" central conductor project from the end of the cable within the axial bore in the connector for engagement with a conductive receptacle in the mating fixture. The prior art connectors work well with standard coaxial cables having a relatively large gauge central conductor because the stripped length is rigid. The rigid conductor can be forced into a spring receptacle in a mating fixture without difficulty. Microcoaxial cables, however, have a small, fragile central conductor. The stripped length of the central conductor in a microcoaxial cable lacks the structural integrity for insertion into a conductive receptacle in a mating fixture. It is current practice to solder or crimp an electrically conductive cap over the stripped length of central conductor in order to provide sufficient rigidity to the central conductor for use with standard connector assemblies. Accordingly, there is a current need for a solderless device and method for adapting the central conductor of a microcoaxial cable for use with standard coaxial cable connectors without the need for soldering or precision crimping.
It is a primary object of the invention to provide a facile means for imparting rigidity to a stripped length of central conductor in a microcoaxial cable.
It is a further object of the invention to provide a facile means for imparting rigidity to a stripped length of central conductor in a microcoaxial cable without requiring either soldering or precision crimping.
It is yet a further object of the invention to provide an electrically conductive pin adapted to fit snugly over a stripped length of a central conductor of a microcoaxial cable, thereafter seizing the central conductor in locking engagement therewith.
It is another object of the invention to provide a tool operable for the facile attachment of an electrically conductive pin to the stripped central conductor of a microcoaxial cable.
The features of the invention believed to be novel are set forth with particularity in the appended claims. However the invention itself, both as to organization and method of operation, together with further objects and advantages thereof may be best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: